For many years optical fibers have been utilized in the medical industry to transmit light (laser energy) to targets for diagnostic as well as therapeutic purposes. Every eye is divided into an anterior and posterior chamber separated by a normally transparent lens which focuses light onto the retina at the back of the posterior chamber. When the lens becomes cloudy for any of a variety of reasons sight is impaired and the cloudy lens must be removed. Following removal of the lens, an inter ocular lens (IOL) implant can be placed in the posterior chamber or thick glasses or contact lenses used to focus the light.
A number of techniques are now in use for this common surgical procedure. An incision can be made in the eye and a sharp instrument inserted to cut and then aspirate by vacuum the cloudy cataract tissue. More recently, a small incision-typically 3 mm-can be made in the eye surface and a metal tipped ultrasonic probe inserted to a position adjacent the lens. The ultrasonic energy then disintegrates the lens material which can likewise be removed by aspiration.
Laser radiation is now used widely in various surgical techniques particularly those involving the eye. For example, the patent to Krasnov, U.S. Pat. No. 3,971,382, describes a technique in which laser radiation is focused onto the anterior capsule of the lens to form a hole through which the cataract substance can be drawn from the lens capsule.
Optical fibers are also commonly used for medical and other applications to transmit coherent radiation from a laser to some location in the body where material is to be coagulated or disintegrated. U.S. patent application Ser. No. 702,569, filed Feb. 19, 1985, describes a micro instrument with an optical fiber. The optical fiber can be inserted into the eye for the removal of abnormal tissue such as tumors. Radiation with a wavelength between 200 and 400 nm is said to be appropriate. However, a problem with laser based systems is that there is the potential for explosions in the eye.
As above mentioned, it is known to use ultrasonic energy to disintegrate cataracts in the eye. This technique is known as phacoemulsification. In such a technique, a metal tip valve is utilized at high frequencies. In such a technique, a metal tip vibrates at high frequencies. The phacoemulsification technique is limited because a metal tip associated therewith becomes very hot at high frequencies, thereby potentially damaging the eye. Due to the heat associated with the high frequency output, the current practice has been to avoid utilizing this technique with hard cataracts.
Accordingly, what is needed is a cataract removal system that does not have the heat problems associated with the phacoemulsification process and also is not susceptible to the explosions generated by laser based systems. The present invention addresses such a need.